Utility meters, including mechanical, electromechanical, and solid state meters, are well known and have been used for many years to measure the consumption of resources such as water, gas and electricity. Water meters, for example, generate data indicative of the consumption of water, where such data is used for billing purposes. Initially, utility meters were mechanical devices. As electronic technology advanced, such technology became smaller and less expensive, and thus, more suitable for use in the highly competitive and cost sensitive utility meter market. As such, the use of electromechanical (hybrid meters) and electronic meters has become more common. Indeed, most modem electricity meters, for example, are electronic meters (static meters).
Traditionally, meter reading personnel would periodically travel to each site where a utility meter was installed, inspect a meter installation and manually record consumption data. The customer would then receive a bill based on such collected data. Today, modem meters are increasingly equipped with Automatic Meter Reading (AMR) capabilities which allow utility meters to automatically communicate data to a remote location. Such technology greatly simplifies and lowers the cost of collecting consumption data for billing purposes.
One problem that confronts designers of utility meters comprising wireless AMR systems, where the utility meters are installed in underground enclosures, relates to the underground environment in which at least part of the AMR system is installed. Wireless AMR systems require a transmitting antenna that converts bound circuit fields into propagating electromagnetic waves. Notably, such antennas can also be configured to remove power from passing electromagnetic waves thereby receiving a transmitted signal. Electromagnetic waves can be deflected, attenuated, and even absorbed by non-RF transparent material, such as the material commonly found in underground enclosure environments. Consequently, a number of attempts have been made to provide a system specifically designed for transmitting data from an underground utility meter to a remote location. Examples of known antenna arrangements for use with underground utility meters are disclosed in U.S. Pat. No. 6,414,605 issued to Walden et al. and U.S. Pat. No. 5,298,894 issued to Cerny et al. and such disclosures are incorporated by this reference for all that they disclose.
One such prior art system comprises an above ground antenna connected to a below ground transmitter through a wired connection. Other prior art systems simply transmit a signal from within the underground enclosure. These prior systems have several design limitations. First, the transmitter is still located within the underground enclosure thereby potentially subjecting the transmitter and the connection between the transmitter and antenna to water contamination. Second, the attenuation inherent in the wired connection between the transmitter and the antenna results in a power loss which lowers system efficiency. Third, where the underground enclosure has a lid and where the antenna and/or transmitter is associated with such lid, removal of such lid without due care can result in damage to the wired connection between the transmitter and the antenna and/or the transmitter and the meter. Consequently, there is a need for a wireless AMR system that (1) improves efficiency by reducing the attenuation between the transmitter and the antenna, (2) better protects the transmitter from the underground enclosure environment, and (3) minimizes the potential of damage to the system when the underground enclosure top is removed.
Yet another issue that designers of utility meter technology face is supplying power to the meter electronics. In many utility meter environments, easily accessible power from an electrical utility grid is not available. As a result, such meter technology is often powered by a power source such a battery. Therefore, there is a need for an apparatus and method for extending the expected life of the power source, such an apparatus for recharging the power source or supplying the power source with a trickle.